Authors:Lucas Anthony Ciccarelli; Christof Breckenfelder, Christoph GrebPages: 1 - 16Abstract: The objective of the presented work is to take advantage of the precision capabilities of tailor-fiber-placement (TFP) embroidery processes in order to qualify carbon-fiber parts as viable antennas for wireless power transfer applications in multifunctional carbon-fiber-reinforced plastic (CFRP) composites. The solution comes first from a literature study of electrical, high-frequency, and textile engineering concepts. This review built familiarity with the technological challenges and state-of-the-art of the presented technology. Next step was iterative experimentation of machine capabilities for the production of carbon-fiber antennas. Finally, antenna prototypes were produced and their physical and electrical characteristics were evaluated through several test methods. The results showed that TFP embroidery machines were capable of producing quality, carbon antennas. Induction values of the antennas from 0.5 to 3.5 ‘H were achieved. Signal transfer efficiencies from carbon-antenna transmitters to an aftermarket receiver show promise in commercial application.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2018.5Issue No:Vol. 6, No. 1 (2019)

Authors:Stasiu Chyczewski; Seahee Hwangbo, Yong-Kyu Yoon, David P. ArnoldPages: 17 - 25Abstract: This article experimentally explores the use of ferrite cores to miniaturize the receivers used for inductive wireless power transmission. A variety of receivers were designed and fabricated using cylindrical ferrite cores, ranging in total size from 47 to 687 mm3. The receivers were tested with a commercially available transmitter operating under the Rezence (Air Fuel Alliance) standard at 6.78 MHz. Experiments measured performance of the receivers in terms of their maximum power draw and efficiency as functions of the receiver load and transmission distance. Experimental results showed that ferrite-core receivers could draw multiple watts of power with end-to-end efficiencies in excess of 50%. While the efficiencies are less than a commercially planar coil receiver, the ferrite-core receivers offer a >50% reduction in mass and >90% reduction in footprint. As a result, the receiver power densities reach up to 17.6 W/cm3, which is a 25× improvement over previously reported work. This effort confirms the viability of ferrite-core receivers for size- and weight-constrained applications.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2018.6Issue No:Vol. 6, No. 1 (2019)

Authors:Yang Yang; Wenjie Chen, Liyu Dai, Rui WangPages: 26 - 40Abstract: Wireless power transmission (WPT) systems with moveable mechanical parts have been acquired more and more attention during the past decade. However, due to the moveable feature of transmitting coil and receiving coil, misalignment issue lead to extra power loss, decrease in efficiency, increase in control complexity, and unwanted performance degradation of the whole system. Moreover, it happened frequently than those traditional planar coils systems. The motivation for this paper is trying to have a deep understanding of quantitative relationship between ball-shaped coils mutual inductance and misalignment. Based upon that, engineers would know more detail of the coils position and mutual inductance. So, optimized design might be achieved. On considering that, this paper presents a WPT system with a ball-shaped coil for robot joints. A mutual inductance calculation based on filament method aimed at ball-shaped coil is proposed. Based on these, nine different ball-shaped coil solutions are calculated. Then, model with a minimized change rate of mutual inductance against the angular misalignment is chosen as the optimized design. Circuit analysis of the WPT system with the series–series resonant topology is conducted to choose a proper working frequency and load. Finally, an experimental platform is established. It demonstrates the feasibility of the proposed calculation method and the feasibility of the WPT prototype.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2019.1Issue No:Vol. 6, No. 1 (2019)

Authors:Qassim S. Abdullahi; Rahil Joshi, Symon K. Podilchak, Sadeque R. Khan, Meixuan Chen, Jean Rooney, John Rooney, Danmei Sun, Marc P.Y. Desmulliez, Apostolos Georgiadis, Dimitris AnagnostouPages: 41 - 56Abstract: Advances in material science and semiconductor technology have enabled a variety of inventions to be implemented in electronic systems and devices used in the medical, telecommunications, and consumer electronics sectors. In this paper, a wireless charging system is described as a wearable body heater that uses a chair as a transmitter (Tx). This system incorporates the widely accepted Qi wireless charging standard. Alignment conditions of a linear three-element coil arrangement and a 3 × 3 coil matrix array are investigated using voltage induced in a coil as a performance indicator. The efficiency obtained is demonstrated to be up to 80% for a voltage of over 6.5 Volts and a power transfer of over 5 Watts. Our results and proposed approach can be useful for many applications. This is because the wireless charging system described herein can help design seating areas for the elderly and disabled, commercial systems, consumer electronics, medical devices, electronic textiles (e-textiles), and other electronic systems and devices.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2019.2Issue No:Vol. 6, No. 1 (2019)

Authors:Takashi Hirakawa; Ce Wang, Naoki ShinoharaPages: 57 - 66Abstract: Microwave power transfer (MPT) can solve certain types of problems. For example, Internet of Things requires a flexible configuration of sensor networks, which is hindered by wired-charging sensors. This problem can be overcome by MPT techniques. However, the transmission efficiency of MPT is lower than that of wired transmission. This study focuses on the operation of rectifiers having a pulse-modulated input signal. Although a pulse-modulated wave is effective for improving the RF-DC conversion efficiency, the output voltage waves of rectifiers have a high ripple content. Moreover, the harmonic balance method cannot be used to simulate the operation of a pulse-modulated rectifier. To reduce the ripple content, a smoothing capacitor should be connected in parallel to an output load. We investigated the influence of a smoothing capacitor, the general characteristics of rectifiers under pulse-modulated waves, and the effectiveness of using pulse-modulated waves for improving RF-DC conversion efficiency. In conclusion, we reveal a necessary condition of the smoothing capacitor for improvement, demonstrate the effectiveness of pulse modulation, and show that the optimum impedance with a pulse-modulated wave input is an inverse of duty ratio times as compared to that with continuous wave input.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2019.3Issue No:Vol. 6, No. 1 (2019)

Authors:Qi Zhu; Hua Han, Mei Su, Aiguo Patrick HuPages: 67 - 76Abstract: More mobile devices such as mobile phones and robots are wirelessly charged for convenience, simplicity, and safety, and it would be desirable to achieve three-dimensional (3D) wireless charging with high spatial freedom and long range. This paper proposes a 3D wireless charging cube with three orthogonal coils and supporting magnetic cores to enhance the magnetic flux outside the cube. The proposed system is simulated by Ansoft Maxwell and implemented by a downsized prototype. Both simulation and experimental results show that the magnetic cores can strengthen the magnitude of B-field outside the cube. The final prototype demonstrates that the power transfer distance outside the cube for getting the same induced electromotive force in the receiver coil is extended approximately by 50 mm using magnetic cores with a permeability of 2800. It is found that the magnitude of B-field outside the cube can be increased by increasing the width and the permeability of the magnetic cores. The measured results show that when the permeability of the magnetic cores is fixed, the induced electromotive force in the receiver coil at a point 300 mm away from the center of the cube is increased by about 2V when the width of the magnetic cores is increased from 50 to 100 mm. The increase in the induced electromotive force at an extended point implies a greater potential of wireless power transfer capability to the power pickup.PubDate: 2019-03-01T00:00:00.000ZDOI: 10.1017/wpt.2019.4Issue No:Vol. 6, No. 1 (2019)